Now that it has been published I can share with you the second part of a two part article I was asked to write for the Portrait Society of America. It was originally published in the Journal of the Portrait Society of America, Volume XII, Issue No. 47. You can find the first part of the article in my April posts. I hope you enjoy it.

In the previous article we stayed much to the physics of what is occurring as light illuminates a form or object, particularly as it concerns our visual perception. In this second part we will look at how this information can be applied through assessment and application. Similar to the great diversity in procedure employed by anatomically informed artists when drawing the figure the information can be applied in a wide variety of ways. For this reason I have decided to offer it based upon some of my own working thoughts and practices. The reader can then adopt, adapt, or reject these thoughts and practices as they see fit.

Color Terminology

As we continue it is necessary to speak in terms of color since the visual artist cannot express light and how it reveals forms without it. I have approached this with an awareness that color terminology varies greatly among artists, especially in the realm of color models and color space, or the arrangement of colors in three dimensions owing to their attributes. The attributes of color that I generally think in terms of are: "hue," a color's quality of being reddish, orangish, yellowish...etc, "value" its lightness or darkness, and chroma, its degree of departure from a particular hue toward a perfectly neutral grey without shifting in value.

Questions and Assessment

When painting, although I have to ask myself about the colors I am seeing and their relationships as a starting point, I feel I can't leave this as my final assessment in determining the correctness of what I have created. I also need to include questions such as: What is happening? What does each mark or stroke of color I put down imply in terms of form and light? And ultimately, does what I have created make sense in terms of how light illuminates form? A similar comparison can be made to an artist drawing the contour of a figure. When doing so they may ask themselves about the tilts and points that compose the contour but ultimately they need to determine if the contour in their drawing correctly reflects the anatomical structure of the figure.

Visualizing the Light Trajectory

I often visualize the spatial relationship between the object and the light. I evaluate the trajectory that the light will travel—imagining lines emitting from the light source touching the object upon various planes. The angle of tangency with which these lines intersect the planes gives me insight into the amount of light they are receiving. (Figure 1)

Even if I can't see the light source, one way I can still assess its trajectory is to look at an object's cast shadow and mentally align a point along its edge with the corresponding, causative, point along the object's terminator (form-shadow line). An example of this in locating the angle of a light source might be to follow an imaginary line from the outer edge of a sundial's shadow up to the top of its needle. A straight line between these two points gives the light's trajectory. For instance, on a portrait the nose and its cast shadow might be utilized to apply this. (Figure 2)

Although a bit too intrusive for portraits another method I've used to check trajectory is to drive a nail into the flat side of a piece of wood like a ruler so that it is perpendicular to its surface. By placing this ruler close to the object I am working from and then tilting the ruler until the cast shadow from the head of the nail perfectly aligns with the nail's base, the tilt of the nail's shaft is now aligned to give the trajectory of the light. (Figure 3)

Surface Planes in Relation to Light Trajectory

With the light's trajectory established I can examine an object's surface planes in relation to the trajectory. From Part I of the article we know on a surface composed of primarily diffuse reflection, unless obscured by specular reflections or altered by other variables such as local color changes, the more these surface planes face away from the light the more they should tend to appear darker in value and weaker in chroma. This progression begins very slowly out in the lights and then speeds up as we move into the half-tones and finally into the shadows. By considering this for each individual plane, the very subtle value and chroma shifts which are nearly indistinguishable by eye often become much more apparent. This assessment of surface planes and the light trajectory for each of them allows me to express very subtle modulations of value and chroma along with their directional gradations.

Using a Sphere to VisualizeSurface Planes in Relation to Light Trajectory

Very often when assessing tilts many artist's compare them to a horizontal and vertical plum line, either real or imagined. This context tends to make their assessments more accurate. In a very similar way the surface planes of an object can be compared to a sphere (often thought of with some degree of faceting) under the same lighting conditions. By assessing a surface plane on the object and comparing it with a surface plane on the sphere that has the same spatial orientation, the sphere gives context to the plane and clearly allows a judgment to be made whether or not it is receiving a lot of light or very little light. This then translates to a clearer sense of what its value and chroma should be relative to other planes. In this way surface planes can also be easily assessed as belonging to a region of light, halftone or shadow. (Figure 4)

The use of a sphere also allows for the comparison of multiple surface planes on an object to see relative color relationships. For example two surface planes on an object may appear visually quite similar in value but once both have been assessed as planes on a sphere it often becomes quite obvious which is lighter and which is darker according to how much light they receive.

Painting Dark to Light or Light to Dark Examining Diffuse Reflection

Whether painting broadly or tightly, the examination of diffuse reflection from either dark to light or light to dark is often a helpful sequence for me. This consideration allows me to anticipate what is likely to happen as I move across the object either away from the light or toward the direction of light. Assuming that I am working in an area of a single local-color, as I progress across the surface from one plane to the next, based upon the light on the form I can anticipate whether it should be lighter or darker in value and stronger or weaker in chroma than the previous plane and skew the mixture(s) on my palette in that direction.

Small pools of paint can be created on the palette one next to the other, each color representing the amount of light a particular plane is reflecting. By placing these pools next to each other on the palette even very delicate modulations of color can be detected and any radical break in the trajectory of the sequence of hue, value or chroma stand out. (Figure 5)

In addition, painting this way allows for the construction of one section of form at a time. In doing this, each section can be evaluated to see if it correctly conveys the form of the object and makes sense in terms of how light illuminates it.

Conclusion

Although this article is limited, both parts focus upon the anatomy of light on form. The expression of this, consciously or unconsciously, is part of every representational artist's consideration. Part I offers a scientific base to be built upon through knowledge and experience. Part II offers ideas for the unitization and conveyance of that science which can be made to serve artistic creativity depending upon individual artistic genius and need. Together they offer points for consideration so that ultimately our thoughts and execution are clearer as we not only see but also understand the why of the representational creative process.

For this post I thought I would share a bit about a distinction that addresses problem solving for the artist in terms of how they "see." It involves two fundamental components that make up visual perception. I have come to know these components as "conceptual" and "optical." I have seen others allude to the same concepts using terms such as impressionistic (optical) and classical (conceptual).

One of my favorite art books, The Practice and Science of Drawing by Harold Speed, has a statement which I have often felt sums up these components quite well:

"We have seen that there are two extreme points of view from which the representation of form can be approached, that of outline directly related to the mental idea of form with its touch association on the one hand, and that of mass connected directly with the visual picture on the retina on the other."

In the same book the author cites work by Michelangelo and Degas to further exemplify the distinction between the two concepts by offering the following (I have supplied an image for each artist although they are not the same images referred to in the book):

"In the Michael Angelo the silhouette is only the result of the overlapping of rich forms considered in the round. Every muscle and bone has been mentally realized as a concrete thing and the drawing made as an expression of this idea. Note the line rhythm also; the sense of energy and movement conveyed by the swinging curves; and compare with what is said later (page 162) about the rhythmic significance of swinging curves."

"Then compare it with the Degas and observe the totally different attitude of mind in which this drawing has been approached. Instead of the outlines being the result of forms felt as concrete things, the silhouette is everywhere considered first, the plastic sense (nowhere so great as in the other) being arrived at from the accurate consideration of the mass shapes."

I sometimes like to think of the optical as the data our eye sees. It is compiled of non-representational shapes (masses) of patterns and color. It is associated with the 2-dimensional picture plane or an impression upon the retina. In contrast the conceptual is the mental understanding or visualization of what is being seen. It is the understanding of an object in terms of how the mind comprehends it based off prior experience or knowledge. It is often simplified or idealized to it make it easier to grasp. It is often associated with 3-dimentional, spatial, geometric and structural ways of thinking and problem solving. When this optical data is filtered through our conceptual understanding the result is our perceptional experience.

Ok, so why is all of this important. Well whether they are conscious of it or not it defines for many artists how they look at things and choose what to look for. Although greatly oversimplified, I have previously described impressionistic painters and classical painters thusly:

"The impressionist collects the data they see and presents the data to the viewer, who then draws a conclusion while the classical painter collects the data they see, draws a conclusion, and then presents the conclusion to the viewer."

More particularly when "seeing" how do these concepts define what artist's look for? Do they look for shapes(optical) or forms(conceptual)? Do they focus on the edges between shapes(optical) or the form's morphology between planes(conceptual)? Do they calculate the lightness or darkness of a stroke of paint by relating the values of various shapes(optical), or mentally visualizing the decay of light over a form(conceptual)? When they utilize a plum line, is it visualized structurally inside the object(conceptual) or at the picture plane like a line drawn on a window(optical)? When they start to draw a head do they start with the shapes they see(optical) or with some structural construct such as an egg form(conceptual)?

Realistically I don't think any artist's work is wholly formed conceptually or optically—although philosophically many seem to favor one approach over the other. For myself I think that all of the questions posed above, both optical and conceptual, are useful. I assume that they should lead me to the same conclusion. Yet that conclusion is formed by meeting my conceptually understood experience thus grouping me more as a classical painter as I previously defined it.

There is so much more that could be said on this simple distinction. However for the readers who are artists I hope it may make you more aware of how you see and for the art collector and enthusiast I hope it will give you more insight into the thoughts of the artists whose work you enjoy.

Just a little food for thought.

An Addendum passage from Harold Speed:

I have included a larger passage below from Harold Speed's book that ties into what has already been said. I wanted to add it on because it has been insightful to me but I couldn't see a good way of working it into what I wrote above.

"To sum up this somewhat rambling chapter, I have endeavoured to show that there are two aspects from which the objective world can be apprehended. There is the purely mental perception founded chiefly on knowledge derived from our sense of touch associated with vision, whose primitive instinct is to put an outline round objects as representing their boundaries in space. And secondly, there is the visual perception, which is concerned with the visual aspects of objects as they appear on the retina; an arrangement of colour shapes, a sort of mosaic of colour. And these two aspects give us two different points of view from which the representation of visible things can be approached.

When the representation from either point of view is carried far enough, the result is very similar. Work built up on outline drawing to which has been added light and shade, colour, aerial perspective, &c., may eventually approximate to the perfect visual appearance. And inversely, representations approached from the point of view of pure vision, the mosaic of colour on the retina, if pushed far enough, may satisfy the mental perception of form with its touch associations. And of course the two points of view are intimately connected. You cannot put an accurate outline round an object without observing the shape it occupies in the field of vision. And it is difficult to consider the "mosaic of colour forms" without being very conscious of the objective significance of the colour masses portrayed. But they present two entirely different and opposite points of view from which the representation of objects can be approached. In considering the subject of drawing I think it necessary to make this division of the subject, and both methods of form expression should be studied by the student. Let us call the first method Line Drawing and the second Mass Drawing. Most modern drawing is a mixture of both these points of view, but they should be studied separately if confusion is to be avoided. If the student neglects line drawing, his work will lack the expressive significance of form that only a feeling for lines seems to have the secret of conveying; while, if he neglects mass drawing, he will be poorly equipped when he comes to express form with a brush full of paint to work with."

In response to my last two posts I have received questions regarding how I transfer my drawings to my linen. I have done different things over the years but usually these days I do an oil-transfer. The main reason I like doing an oil-transfer is that it doesn't introduce any other materials such as charcoal or graphite into the painting.

Here are instructions for how to do an oil-transfer. The content has been taken from a handout I made up for my painting workshops:

Step 1. Take a good photocopy (the darker the lines the better) of your drawing (or the drawing itself if the paper is not too thick) and hold it up to a light so that the image is facing away from you and toward the light. On the backside of the paper (not the side with the image) roughly outline the areas you will need to apply oil paint to, so that you don't have to cover the entire back of the paper.

Step 2. Put out some raw umber on your palette (do not add anything to it). Using a large bristle brush, dry brush or scumble (scrub) the paint onto the back of your photocopy (the side without the image) in the areas you outlined in step "1." Try for an even, fairly thin coat.

Step 3. Place your photocopy on your canvas or linen with the oil side face down, touching the canvas or linen. Be careful to keep the drawing aligned so that your image is not crooked. With your image carefully placed, securely tape one side of the paper to keep it from moving.

Step 4. Trace over your drawing using a ball point pen. A red pen makes it easier to keep track of where you have traced. Be careful not to rest your hand on the drawing—instead rest your hand on your mahl stick as you trace. Periodically (and carefully) flip up your image to make sure the transfer is working.

Step 5. With the tracing done, remove the photocopy and the tape. Allow the canvas to dry overnight—or more preferably, a few days.